Low-temperature Structure Research Articles

Pre-existing orthorhombic embryos-induced hexagonal–orthorhombic martensitic transformation in MnNiSi1–x (CoNiGe) x alloy

The thermal–elastic martensitic transformation from high-temperature Ni2In-type hexagonal structure to low-temperature TiNiSi-type orthorhombic structure has been widely studied in MnMX (M = Ni or Co, and X = Ge or Si) alloys. However, the answer to how the orthorhombic martensite nucleates and grows within the hexagonal parent is still unclear. In this work, the hexagonal–orthorhombic martensitic transformation in a Co and Ge co-substituted MnNiSi is investigated. One can find some orthorhombic laths embedded in the hexagonal parent at a temperature above the martensitic transformation start temperature (M s). With the the sample cooing to M s, the laths turn broader, indicating that the martensitic transformation starts from these pre-existing orthorhombic laths. Microstructure observation suggests that these pre-existing orthorhombic laths do not originate from the hexagonal–orthorhombic martensitic transformation because of the difference between atomic occupations of doping elements in the hexagonal parent and those in the pre-existing orthorhombic laths. The phenomenological crystallographic theory and experimental investigations prove that the pre-existing orthorhombic lath and generated orthorhombic martensite have the same crystallography relationship to the hexagonal parent. Therefore, the orthorhombic martensite can take these pre-existing laths as embryos and grow up. This work implies that the martensitic transformation in MnNiSi1−x (CoNiGe) x alloy is initiated by orthorhombic embryos.

(Invited) Electrolytes for Next-Generation Sodium Metal Batteries

Developing reliable and cost-effective electrical energy storage systems (EESs) for portable electronics, electric vehicles, and grid storage applications is vital. Na-ion batteries are the most promising alternative technology owing to their natural abundance and low sodium cost.[1] Solid-state batteries (SSBs) have garnered extensive attention for their ability to suppress the safety hazards of organic liquid electrolytes by replacing them with solid electrolytes.[2] Among the various solid electrolytes being explored, our group mainly focuses on NASICON (Sodium superionic conductor) type silicate and solid polymer electrolytes. Sodium silicates are a class of materials with composition, NaxMxSixOx (M = rare-earth metals, x = integer (1-10)).[3] They have the advantage of low sintering temperature (~1050 °C) and 3D framework structure containing MO6 octahedra and SiO4 tetrahedra providing facile ionic movement.[4] Solid polymer electrolytes (SPE) are known for their flexibility and electrode compatibility. Highly conductive, filler-free composite solid polymer electrolyte films were prepared using poly(vinylidene fluoride), poly(vinyl pyrrolidone) (PVP), and NaPF6.[5] PVP binder played an essential role in improving Na ion conductivity and excellent plating−stripping performance. This talk will present an overview of these solid electrolytes for next-generation sodium metal batteries.

Effect of Substrates on the Physicochemical Properties of Li7La3Zr2O12 Films Obtained by Electrophoretic Deposition.

Thin film technology of lithium-ion solid electrolytes should be developed for the creation of all-solid-state power sources. Solid electrolytes of the Li7La3Zr2O12 (LLZ) family are one of the promising membranes for all-solid-state batteries. LLZ films were obtained by electrophoretic deposition on Ti, Ni and steel substrates. The influence of different metal substrates on microstructure, phase composition and conductivity of the LLZ films after their heat treatment was studied. It was shown that the annealing of dried LLZ films in an Ar atmosphere leads to the transition from tetragonal modification to a low-temperature cubic structure. It was established that an impurity phase (Li2CO3) was not observed for LLZ films deposited on Ti foil after heat treatment, in contrast to films deposited on Ni and steel substrates. The highest lithium-ion conductivity values were achieved for the LLZ films annealed at 300 °C, 1.1 × 10-8 S cm-1 (at 100 °C) and 1.0 × 10-6 S cm-1 (at 200 °C).

Synergistic effect of surface modified nano-zinc oxide and organic vermiculite on long-term ultraviolet and thermal-oxidative aging resistance of different asphalt binders

Asphalt pavement will be subjected to the action of thermal, oxygen and ultraviolet during long-term service, which in turn causes the ultraviolet and thermal-oxidative aging of asphalt simultaneously. Based on the long-term aging mechanism, the double retarding effect of surface modified nano-zinc oxide (ZnO) and organic vermiculite (OEVMT) in different stages of long-term aging was utilized in the research. This work investigated the synergistic effect of ZnO and OEVMT on rheological properties and chemical structures of base asphalts (70# and SK-70) and polymer modified asphalts (SBS modified asphalt and SBR modified asphalt) after long-term ultraviolet and thermal-oxidative aging. Dynamic shear rheological (DSR), bending beam rheological (BBR) and Fourier infrared spectroscopy tests were utilized to study the DSR properties, BBR properties at low temperature and chemical structures, respectively. Meanwhile, the synergistic effect mechanism was analyzed. Results showed that the effect of 1 % ZnO to resist the long-term ultraviolet aging of 70# base asphalt approximates that of 3 % OEVMT, while the long-term thermal-oxidative anti-aging ability of 1 % OEVMT for 70# base asphalt is equivalent to that of 3 % ZnO. Besides, compared with 2 % ZnO or 2 % OEVMT, 1 % ZnO + 1 % OEVMT shows a better long-term ultraviolet and thermal-oxidative aging resistance for different asphalt binders, indicating its synergistic effect in strengthening the anti-aging performance of asphalt. Moreover, 1 % ZnO + 1 % OEVMT not only can effectively retard the oxidation rate of asphalt in the process of long-term aging, but also inhibit the degradation degree of modifiers in SBS modified asphalt. The research could propose a new design idea to effectively solve the long-term aging problem of asphalt.

Low-Temperature Predicted Structures of Ag2S (Silver Sulfide).

Silver sulfide phases, such as body-centered cubic argentite and monoclinic acanthite, are widely known. Traditionally, acanthite is regarded as the only low-temperature phase of silver sulfide. However, the possible existence of other low-temperature phases of silver sulfide cannot be ruled out. Until now, there have been only a few suggestions about low-temperature Ag2S phases that differ from monoclinic acanthite. The lack of a uniform approach has hampered the prediction of such phases. In this work, the use of such an effective tool as an evolutionary algorithm for the first time made it possible to perform a broad search for the model Ag2S phases of silver sulfide, which are low-temperature with respect to cubic argentite. The possibility of forming Ag2S phases with cubic, tetragonal, orthorhombic, trigonal, monoclinic, and triclinic symmetry is considered. The calculation of the cohesion energy and the formation enthalpy show, for the first time, that the formation of low-symmetry Ag2S phases is energetically most favorable. The elastic stiffness constants cij of all predicted Ag2S phases are computed, and their mechanical stability is determined. The densities of the electronic states of the predicted Ag2S phases are calculated. The prediction of low-temperature Ag2S structures indicates the possibility of synthesizing new silver sulfide phases with improved properties.

Revisiting the structures and phase transitions of Ba2NaNb5O15.

The room-temperature and low-temperature structure(s) of Ba2NaNb5O15 (BNN) have been debated since the structure was proposed in the 1960s. This work revisits the structures and phase transitions of BNN, combining high-resolution X-ray and neutron powder diffraction with density functional theory calculations. Temperature-dependent high-resolution X-ray powder diffraction patterns are collected from 4 to 918 K, and sequential batch Rietveld refinement using a symmetry mode approach to describe the structure is used to extract the main structural changes as a function of temperature. The data show that the average structure of BNN is best described by the Ama2 space group, and no other structural phase transitions were observed below the ferroelastic transition. The symmetry mode analysis, combining results from diffraction and density functional theory, shows significant octahedral tilting and corrugations of both the A1 and A2 sites along the c direction. A strong correlation between the spontaneous strain and the octahedral tilting was observed, and a potential connection with emerging microstructure at low temperatures is proposed, all enabled by the symmetry mode approach used in this work.

Multi-objective optimization of precooled JT cryocooler working at liquid hydrogen temperature

With the advantages of no moving parts at low temperature, flexibility and simple structure, the precooled Joule-Thomson (JT) cryocooler working at liquid hydrogen temperature has the potential to be applied in the liquid hydrogen zero boil-off (ZBO) storage system in space. For JT cryocooler used in aerospace, cooling capacity, efficiency and mass are key parameters which should be considered simultaneously. For this reason, in this study, a theoretical model of the precooled JT cryocooler working at liquid hydrogen temperature which is composed of the heat exchangers, the JT compressor and the precooler is established. The target cooling capacity of the cryocooler is 10 W at liquid hydrogen temperature. Multi-objective optimization method is introduced to comprehensively optimize input power and mass. The Pareto frontier consisting of a series of non-dominated solutions is obtained. The linear programming technology of multidimensional analysis preference (LINMAP) method is used to select the final optimal solution from the Pareto frontier. The multi-objective optimization results of input power and mass of the cryocooler are 3484.72 W and 40.92 kg, respectively.

Free-Base Corrole Anion.

Free-base corroles have long been known to be acidic, readily undergoing deprotonation by mild bases and in polar solvents. The conjugate base, however, has not been structurally characterized until now. Presented here is a first crystal structure of a free-base corrole anion, derived from tris(p-cyanophenyl)corrole, as the tetrabuylammonium salt. The low-temperature (100 K) structure reveals localized hydrogens on a pair of opposite pyrrole nitrogens. DFT calculations identify such a structure as the global minimum but also point to two cis tautomers only 4-7 kcal/mol above the ground state. In terms of free energy, however, the cis tautomers are above or essentially flush with the trans-to-cis barrier so the cis tautomers are unlikely to exist or be observed as true intermediates. Thus, the hydrogen bond within each dipyrrin unit on either side of the molecular pseudo-C2 axis through C10 (i.e., between pyrrole rings A and B or between C and D) qualifies as or closely approaches a low-barrier hydrogen bond. Proton migration across the pseudo-C2 axis entails much higher activation energies >20 kcal/mol, reflecting the relative rigidity of the molecule along the C1-C19 pyrrole-pyrrole linkage.

Strong Host-Guest Dependence on the Emissive Properties of MOF-5 and [Zn2(BTTB)(DMF)2•(H2O)3]n.

3D-[Zn4O(1,4-BDC)3•x(solvent)]n (MOF-5; BDC = 1,4-benzodicarboxylate) and 3D-[Zn2(BTTB)(DMF)2•(H2O)3]n (MOF-D; BTTB = 4,4',4″,4‴-benzene-1,2,4,5-tetrayltetrabenzoate) have been investigated by means of steady-state UV-visible and fluorescence and time-resolved emission spectroscopy, as a function of solvent and power of the excitation irradiation. The low-temperature X-ray structures (173 K) were permitted to locate solvent molecules (here H2O) in the lattice. They were found distributed in the middle in the voids with no evidence of specific interactions (H-bond, coulombic, and dipole-dipole) with the framework. The fluorescence decays of the ligands (ππ* excited state), τF, for the host-guest composites MOF-5@solvent and MOF-D@solvent (solvent = air, MeCN, EtCN, MeOH, EtOH, and DMF) were found bi-exponential (short τF1 (ps), and long τF2 (ns)) with one important feature: upon cooling from 298 to 77 K, MOF-5's τF1 decreases and τF2 increases, while the opposite trend is generally observed in MOF-D. The low values for τF1 (ps) in MOF-5 are associated with the augmented probability of solvent-ligand collisions leading to nonradiative deactivation, which upon cooling to 77 K increases further as the scaffolding contracts. The augmentation in τF2 is readily associated with the increased rigidity of the ligands that are not submitted to this effect (at the surface of the MOF and as pendent groups). For the low emitter MOF-D, the reversed situation is noted but not as clearly due to the uncertainties in the data. Upon increasing the excitation flux, the fluorescence intensity increases linearly with the laser power indicating the absence of singlet-singlet annihilation, inferring the absence of efficient exciton migration. This observation is explained by the small absorptivity coefficients, which leads to a small J spectral overlap between absorption and fluorescence according to the Forster and Dexter theories, and consequently, a small rate for energy migration. This conclusion drastically changes the perception of the photocatalytic mechanism of MOF-5 and other MOFs exhibiting similar absorption features (i.e., no antenna effect).

Electrical properties of a low-temperature fabricated Ge-based top-gate MOSFET structure with epitaxial ferromagnetic Heusler-alloy Schottky-tunnel source and drain

We show electrical properties of a Ge-based top-gate metal-oxide-semiconductor field-effect transistor (MOSFET) structure with epitaxial ferromagnetic Heusler alloy/Ge Schottky-tunnel contacts, fabricated with a low-temperature gate-stack process. For shaping the Ge-MOSFET with the ferromagnetic source and drain (S/D) contacts, we use a combination process of Ar+ ion milling and reactive ion etching (RIE). As a consequence of the formation of a gate stack (SiO2/GeO2) using a process temperature of 240 °C, we demonstrate inversion channel MOSFETs with a low gate-voltage operation (VG ∼5 V). Furthermore, we achieve a relatively high field-effect mobility (μFE) of ∼300 cm2/Vs compared to those in a Si-based back-gate spin-MOSFET reported previously [Phys. Rev. B 102, 035305 (2020).]. This study will open a way for developing a Ge-based top-gate spin-MOSFET on the Si platform.

Integrated NMR/Molecular Dynamics Determination of the Ensemble Conformation of a Thermodynamically Stable CUUG RNA Tetraloop.

Both experimental and theoretical structure determinations of RNAs have remained challenging due to the intrinsic dynamics of RNAs. We report here an integrated nuclear magnetic resonance/molecular dynamics (NMR/MD) structure determination approach to describe the dynamic structure of the CUUG tetraloop. We show that the tetraloop undergoes substantial dynamics, leading to averaging of the experimental data. These dynamics are particularly linked to the temperature-dependent presence of a hydrogen bond within the tetraloop. Interpreting the NMR data by a single structure represents the low-temperature structure well but fails to capture all conformational states occurring at a higher temperature. We integrate MD simulations, starting from structures of CUUG tetraloops within the Protein Data Bank, with an extensive set of NMR data, and provide a structural ensemble that describes the dynamic nature of the tetraloop and the experimental NMR data well. We thus show that one of the most stable and frequently found RNA tetraloops displays substantial dynamics, warranting such an integrated structural approach.

Strengthening Aqueous Electrolytes without Strengthening Water.

Aqueous electrolytes typically suffer from poor electrochemical stability; however, eutectic aqueous solutions-25 wt.% LiCl and 62 wt.% H3 PO4 -cooled to -78 °C exhibit a significantly widened stability window. Integrated experimental and simulation results reveal that, upon cooling, Li+ ions become less hydrated and pair up with Cl- , ice-like water clusters form, and H⋅⋅⋅Cl- bonding strengthens. Surprisingly, this low-temperature solvation structure does not strengthen water molecules' O-H bond, bucking the conventional wisdom that increasing water's stability requires stiffening the O-H covalent bond. We propose a more general mechanism for water's low temperature inertness in the electrolyte: less favorable solvation of OH- and H+ , the byproducts of hydrogen and oxygen evolution reactions. To showcase this stability, we demonstrate an aqueous Li-ion battery using LiMn2 O4 cathode and CuSe anode with a high energy density of 109 Wh/kg. These results highlight the potential of aqueous batteries for polar and extraterrestrial missions.

Effect of Li2CO3–Bi2O3 doping on the low-temperature sintering, structure, and dielectric and mechanical properties of MgO–TiO2(w) ceramics

Dense MgO–12% TiO2(w) ceramics containing 12 wt% TiO2, which were doped with Li2CO3–Bi2O3 composite sintering aids, were prepared at a low sintering temperature of 950 °C in this study. The effects of sintering additives on the sintering characteristics, phase composition, microstructure, and dielectric and mechanical properties of the ceramic samples were systematically investigated, and the influences of their phase composition and microstructure on the dielectric and mechanical properties were examined. The introduction of sintering aids produced a new Bi4Ti3O12 phase in the sample structure, while the residual Bi2O3 mixed with the newly formed Mg2TiO4 and Bi4Ti3O12 phases distributed at MgO grain boundaries formed a structure surrounding MgO grains. This structure filled the pores in the ceramic sample, which increased its density and enhanced the mechanical properties. At a Li2CO3–Bi2O3 content of 15 wt%, the density, flexural strength, and Vickers hardness of the ceramic samples reached their maximum values of 3.4 g/cm3, 218.9 MPa, and 778.7 HV, respectively. However, the further increase in the Li2CO3–Bi2O3 content deteriorated their dielectric properties although the dielectric constant and dielectric loss remained below 13.4 and 2.1 × 10−3, respectively. The findings of this work indicate that Li2CO3–Bi2O3 sintering aids can significantly lower the sintering temperature of MgO–12% TiO2(w) ceramics and control their dielectric and mechanical properties through microstructural changes.

Gas-pressurized torrefaction of lignocellulosic solid wastes: Low-temperature deoxygenation and chemical structure evolution mechanisms

A novel gas-pressurized (GP) torrefaction realizes deeper deoxygenation of lignocellulosic solid wastes (LSW) to as high as 79% compared to traditional torrefaction (AP) with the oxygen removal of 40% at the same temperature. However, the deoxygenation and chemical structure evolution mechanisms of LSW during GP torrefaction are currently unclear. In this work, the reaction process and mechanism of GP torrefaction were studied through follow-up analysis of the three-phase products. Results demonstrate gas pressure causes over 90.4% of cellulose decomposition and the conversion of volatile matter to fixed carbon through secondary polymerization reactions. Above phenomena are completely absent during AP torrefaction. A deoxygenation and structure evolution mechanism model is developed through analysis of fingerprint molecule and C structure. This model not only provides theoretical guidance for optimization of the GP torrefaction, but also contributes to the mechanism understanding of pressurized thermal conversion processes of solid fuel, such as coal and biomass.

Reactive e-beam evaporated SnOx layer as an effective ETL for highly efficient spray-coated perovskite solar cells

The spray-coating deposition method can extend the use of perovskite solar modules to substrates with different shapes and curvatures that can be used in various parts of buildings and vehicles to maximize the use of solar energy. Due to the lack of centrifugal forces in this method, unlike spin-coating, the quality of the deposited perovskite layer highly depends on the wettability and uniformity of the under layer. In this project, the SnOx layer is deposited by the reactive electron beam evaporation method (re-SnOx) as an electron transport layer for the spray-coated Cs0.05FA0.81MA0.14PbI2.55Br0.45 layer. Results show that spray-coated perovskite (PSK) layers are significantly more uniform on re-SnOx layers compared to the spin-coated commercial nanoparticles of SnOx (np-SnOx) due to their excellent surface coverage and purity. The best efficiency of 20.8% is obtained for re-SnOx/spray-coated PSK. Surface passivation of spray-coated PSK with phenethylammonium iodide improves all photovoltaic properties, increases efficiency from an average of 17.9%–19.6%, and reduces the hysteresis index from an average of 0.3 to 0.09. This low-temperature structure can be fabricated on plastic substrates, as well.

Verwey transition as evolution from electronic nematicity to trimerons via electron-phonon coupling.

Understanding the driving mechanisms behind metal-insulator transitions (MITs) is a critical step toward controlling material's properties. Since the proposal of charge order-induced MIT in magnetite Fe3O4 in 1939 by Verwey, the nature of the charge order and its role in the transition have remained elusive. Recently, a trimeron order was found in the low-temperature structure of Fe3O4; however, the expected transition entropy change in forming trimeron is greater than the observed value, which arises a reexamination of the ground state in the high-temperature phase. Here, we use electron diffraction to unveil that a nematic charge order on particular Fe sites emerges in the high-temperature structure of bulk Fe3O4 and that, upon cooling, a competitive intertwining of charge and lattice orders arouses the Verwey transition. Our findings discover an unconventional type of electronic nematicity in correlated materials and offer innovative insights into the transition mechanism in Fe3O4 via the electron-phonon coupling.

Synthesis and anisotropic magnetic properties of LiCrTe single crystals with a triangular-lattice antiferromagnetic structure

We report on the synthesis of LiCrTe single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find LiCrTe to crystallize in a TlCdS -type structure with cell parameters of a = 3.9512(5) Å and c = 6.6196(7) Å at T = 175 K. The content of lithium in these crystals was determined to be neary stoichiometric by means of neutron diffraction. We find a pronounced magnetic transition at = 144 K and = 148 K, respectively. These transition temperatures are substantially higher than earlier reports on polycrystalline samples. We have performed neutron powder diffraction measurements that reveal that the long-range low-temperature magnetic structure of single crystalline LiCrTe is an A-type antiferromagnetic structure. Our DFT calculations are in good agreement with these experimental observations. We find the system to be easy axis with moments oriented along the c-direction experimentally as well as in our calculations. Thereby, the magnetic Hamiltonian can be written as with K (where ). We find LiCrTe to be highly anisotropic, with a pronounced metamagnetic transition for with a critical field of (5 K) ≈ 2.5 T. Using detailed orientation-dependent magnetization measurements, we have determined the magnetic phase diagram of this material. Our findings suggest that LiCrTe is a promising material for exploring the interplay between crystal structure and magnetism, and could have potential applications in spin-based 2D devices.

Comparison between the intermolecular interactions in the liquid and solid forms of propellant 1,1,1,2 – Tetrafluoroethane

A multitude of metered dose inhaler (MDI) formulation properties, such as permanent particle growth or separation, can affect the device’s drug delivering performance. 1,1,1,2 – Tetrafluoroethane (HFA-134a) is a liquid propellant commonly employed in MDIs. Here molecular modelling approaches are reported to evaluate the effect weak hydrogen bonding and steric repulsions have on its solid and liquid state molecular-scale structure. Molecular dynamics (MD) simulations of pure liquid HFA-134a were completed for a range of temperatures (203 – 323 K) and intermolecular interactions were analysed using the molecular trajectory files generated. Empirical force fields were used to calculate the strength of interactions seen in the low-temperature crystal structure, and these were compared to the liquid.The solid-state intermolecular structure arranges to maximise attractive interactions between permanent dipoles which enables the formation of ‘weak hydrogen bonds’, these were found to guide the transition from body centred cubic to its low temperature, monoclinic phase. Reducing HFA-134a’s liquid phase temperature increases its resemblance to the believed body centred cubic structure, with improved similarity between intermolecular radial distribution functions and vector angles. Weak hydrogen bonds in the liquid occurred more frequently at lower temperatures but the minimisation of steric repulsions is identified as the main cause of structural ordering, this shows liquid propellant is relatively non-polar. Understanding the structure of pure propellant is useful when evaluating the variation in wetting between different formulation materials and has the potential to be a useful resource for digital drug product design.

Order-disorder phase transition driven by interlayer sliding in lead iodides

A variety of phase transitions have been found in two-dimensional layered materials, but some of their atomic-scale mechanisms are hard to clearly understand. Here, we report the discovery of a phase transition whose mechanism is identified as interlayer sliding in lead iodides, a layered material widely used to synthesize lead halide perovskites. The low-temperature crystal structure of lead iodides is found not 2H polytype as known before, but non-centrosymmetric 4H polytype. This undergoes the order-disorder phase transition characterized by the abrupt spectral broadening of valence bands, taken by angle-resolved photoemission, at the critical temperature of 120 K. It is accompanied by drastic changes in simultaneously taken photocurrent and photoluminescence. The transmission electron microscopy is used to reveal that lead iodide layers stacked in the form of 4H polytype at low temperatures irregularly slide over each other above 120 K, which can be explained by the low energy barrier of only 10.6 meV/atom estimated by first principles calculations. Our findings suggest that interlayer sliding is a key mechanism of the phase transitions in layered materials, which can significantly affect optoelectronic and optical characteristics.

Thermal properties of rocks from deep boreholes in Poland in terms of obtaining geothermal energy from enhanced geothermal systems

In the case of unconventional geothermal systems, the thermal conditions are decisive, i.e. heat flux and temperature at a certain depth, and the physical properties of rocks, their susceptibility to fracturing, etc., which should be determined on a local scale. The work carried out was aimed at determining the basic thermal parameters of rocks, i.e.: effusivity, thermal conductivity and diffusivity, basing on tests of samples taken from boreholes, representing selected geothermal structures in Poland. Both high-temperature structures (100-135 °C) recognized up to a depth of about 3,800 m within the Fore-Sudetic Monocline and up to about 3,000 m in the Szczecin Synclinorium and the Leba Elevation, as well as medium-temperature structures (60-90 °C), occurring at depth 2,000- 2,500 m (Warszawa Synclinorium, Lublin Synclinorium), were analyzed. Some samples representing low temperature structures (with temperatures below 60 °C), such as Lublin synclinorium and Podlasie-Lublin elevation from depths from about 1,000 to 1,500 m, were also analyzed. The tests of thermal parameters of rocks coupled with simulations showed, that the formations with the highest mean diffusivity and thermal conductivity values are characterized by the largest thermal penetration depth and smallest temperature drop. The research allowed to conclude that among the examined rocks, the Cambrian sandstones of the Leba Elevation and the Zechstein dolomites of the Fore-Sudetic monocline are characterized by the most appropriate parameters from the point of view of obtaining geothermal energy from the enhanced geothermal systems in Poland. Cited as: Labus, K., Labus, M., Leśniak, G. Thermal properties of rocks from deep boreholes in Poland in terms of obtaining geothermal energy from enhanced geothermal systems. Advances in Geo-Energy Research, 2023, 8(2): 76-88. https://doi.org/10.46690/ager.2023.05.02